1. Field of the Invention
The invention relates in general to a pixel circuit structure, and more particularly to a pixel circuit structure applied in a liquid crystal display panel.
2. Description of the Related Art
The consumption market of consumer electronic products, such as personal digital assistants (PDAs), mobile phones, laptops, projectors, and even large-size flat panel televisions, expands rapidly in recent years, and therefore facilitates the increment of the quantity demanded for liquid crystal display (LCD) panel. Further, along with the maturity of the market and the progress of the technology, consumers are demanding for higher and higher display quality of LCD panels.
Referring to FIG. 1, a perspective of a single pixel in a conventional transflective LCD panel is illustrated. Generally, the conventional transflective LCD panel 10 includes an upper substrate 14, a lower substrate 11 and a liquid crystal (LC) layer 15 filled between the upper substrate 14 and the lower substrate 11. The single pixel of the transflective LCD panel 10 has a transmissive area a1 and a reflective area a2. The transflective LCD panel 10 further includes an organic layer 16 which is disposed at a location on the lower substrate 11 corresponding to the reflective area a2. A transparent electrode 12 and a reflective electrode 17 are disposed on the surface of the lower substrate 11. The transparent electrode 12 is substantially situated in the transmissive area a1, and the reflective electrode 17 is substantially situated in the reflective area a2. The transparent electrode 12 and the reflective electrode 17 are electrically connected to each other. Further, a common electrode 13 is disposed on the surface of the upper substrate 14. The aligning direction of LC molecules is changed according to the magnitude of the voltages applied to the transparent electrode 12 and the reflective electrode 17 relative to the common electrode 13. The source light e1 provided by the backlight module 20 passes through the lower substrate 11 and the transparent electrode 12 in the transmissive area a1 to enter the transflective LCD panel 10, and then goes through the LC layer 15, the common electrode 13 and the upper substrate 14 in order to display pictures. The ambient light e2 passes through the upper substrate 14 and the common electrode 13 to enter the transflective LCD panel 10, and the entered light reflects off the reflective electrode 17 as reached, and then the reflected light passes through the common electrode 13 and the upper substrate 14 again to leave the transflective LCD panel 10.
The light transmittance of the LC layer 15 changes in accordance with the alignment of the LC molecules, and the display component may show multiple grayscale brightness by controlling the voltages applied to the transparent electrode 12 and the reflective electrode 17 relative to the common electrode 13. The organic layer 16 is provided with a thickness, making the gap d2 in the reflective area a2 smaller than the gap d1 in the transmissive area a1. Therefore, the source light e1 in the transmissive area a1 and the ambient light e2 in the reflective area a2 have the same light path difference, so as to improve the optical characteristics of the LC layer 15. However, utilizing the dual gap structure lowers the yield rate, and leads to increases in the manufacturing complexity and the cost. Moreover, the overall uniformity of contrast, color saturation and light transmittance of the transflective LCD panel 10 may be degraded due to the uneven thickness of the organic layer 16 in the dual gap structure.
In addition, transmissive or transflective multi-domain vertical alignment (MVA) technology is often applied in LCDs to meet the demands of features including high contrast ratio, fast response, and wide-viewing angle.
Conventionally, transmissive or transflective MVA LCDs can achieve wide-viewing angles. However, transmissive or transflective MVA LCDs would lead to an undesirable phenomenon of color shift. That is, when a user views the transmissive or transflective MVA LCD with a large viewing-angle, the color of the image viewed by the user would be washed out.